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1
Preece, John Christopher. "Oxygenated hydrocarbon fuels for solid oxide fuel cells." Thesis, University of Birmingham, 2006. http://etheses.bham.ac.uk//id/eprint/117/.
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In order to mitigate the effects of climate change and reduce dependence on fossil fuels, carbon-neutral methods of electricity generation are required. Solid oxide fuel cells (SOFCs) have the potential to operate at high efficiencies, while liquid hydrocarbon fuels require little or no new infrastructure and can be manufactured sustainably. Using hydrocarbons in SOFCs introduces the problem of carbon deposition, which can be reduced or eliminated by judicious choice of the SOFC materials, the operating conditions or the fuel itself. The aim of this project was to investigate the relationships between fuel composition and SOFC performance, and thus to formulate fuels which would perform well independent of catalyst or operating conditions. Three principal hypotheses were studied. Any SOFC fuel has to be oxidised, and for hydrocarbons both carbon-oxygen and hydrogen-oxygen bonds have to be formed. Oxygenated fuels contain these bonds already (for example, alcohols and carboxylic acids), and so may react more easily. Higher hydrocarbons are known to deposit carbon readily, which may be due to a tendency to decompose through the breaking of a C-C bond. Removing C-C bonds from a molecule (for example, ethers and amides) may reduce this tendency. Fuels are typically diluted with water, which improves reforming but reduces the energy density. If an oxidising agent could also act as a fuel, then overall efficiency would improve. Various fuels, with carbon content ranging from one to four atoms per molecule, were used in microtubular SOFCs. To investigate the effect of oxygenation level, alcohols and and carboxylic acids were compared. The equivalent ethers, esters and amides were also tested to eliminate carbon-carbon bonding. Some fuels were then mixed with methanoic acid to improve energy density. Exhaust gases were analysed with mass spectrometry, electrical performance with a datalogging potentiostat and carbon deposition rates with temperature-programmed oxidation. It was found that oxygenating a fuel improves reforming and reduces the rate of carbon deposition through a favourable route to CO/CO2. Eliminating carbon-carbon bonds from a molecule also reduces carbon deposition. The principal advantage of blending with methanoic acid was the ability to formulate a single phase fuel with molecules previously immiscible with water.
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Hung, Tak Cheong. "Fuel reforming for fuel cell application /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CENG%202006%20HUNG.
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ROMANATO, LUIZ S. "Armazenagem de combustivel nuclear queimado." reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11204.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP
4
Zhang, Mingming. "Properties of bio-oil based fuel mixtures: biochar/bio-oil slurry fuels and glycerol/bio-oil fuel blends." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/1825.
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This thesis reports the properties of bio-oil-based fuel mixtures. For bioslurry fuels, the interaction between biochar and bio-oil results in changes in fuel properties and the redistribution of inorganic species. For glycerol/methanol/bio-oil (GMB) fuel blends, the solubility and fuel properties are improved upon methanol addition but other impurities in crude glycerol worsen the solubility with limited impact on properties. It is also possible to integrate the GMB blends production into the biodiesel production process.
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Clarke, Adrian James. "The conceptual design of novel future UAV's incorporating advanced technology research components." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7163.
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There is at present some uncertainty as to what the roles and requirements of the next generation of UAVs might be and the configurations that might be adopted. The incorporation of technological features on these designs is also a significant driving force in their configuration, efficiency, performance abilities and operational requirements. The objective of this project is thus to provide some insight into what the next generation of technologies might be and what their impact would be on the rest of the aircraft.
This work involved the conceptual designs of two new relevant full-scale UAVs which were used to integrate a select number of these advanced technologies. The project was a CASE award which was linked to the Flaviir research programme for advanced UAV technologies. Thus, the technologies investigated during this study were selected with respect to the objectives of the Flaviir project. These were either relative to those already being developed as course of the Flaviir project or others from elsewhere. As course of this project, two technologies have been identified and evaluated which fit this criterion and show potential for use on future aircraft. Thus we have been able to make a contirubtion knowledge in two gaps in current aerospace technology.
The first of these studies was to investigate the feasibility of using a low cost mechanical thrust vectoring system as used on the X-31, to replace conventional control surfaces. This is an alternative to the fluidic thrust vectoring devices being proposed by the Flaviir project for this task. The second study is to investigate the use of fuel reformer based fuel cell system to supply power to an all-electric power train which will be a means of primary propulsion. A number of different fuels were investigated for such a system with methanol showing the greatest promise and has been shown to have a number of distinct advantages over the traditional fuel for fuel cells (hydrogen).
Each of these technologies was integrated onto the baseline conceptual design which was identified as that most suitable to each technology. A UCAV configuration was selected for the thrust vectoring system while a MALE configuration was selected for the fuel cell propulsion system. Each aircraft was a new design which was developed specifically for the needs of this project. Analysis of these baseline configurations with and without the technologies allowed an assessment to be made of the viability of these technologies.
The benefits of the thrust vectoring system were evaluated at take-off, cruise and landing. It showed no benefit at take-off and landing which was due to its location on the very aft of the airframe. At cruise, its performance and efficiency was shown to be comparable to that of a conventional configuration utilizing elevons and expected to be comparable to the fluidic devices developed by the Flaviir project. This system does however offer a number of benefits over many other nozzle configurations of improved stealth due to significant exhaust nozzle shielding.The fuel reformer based fuel cell system was evaluated in both all-electric and hybrid configurations. In the ell-electric configuration, the conventional turboprop engine was completely replaced with an all-electric powertrain. This system was shown to have an inferior fuel consumption compared to a turboprop engine and thus the hybrid system was conceived. In this system, the fuel cell is only used at loiter with the turboprop engine being retained for all other flight phases. For the same quantity of fuel, a reduction in loiter time of 24% was experienced (compared to the baseline turboprop) but such a system does have benefits of reduced emissions and IR signature. With further refinement, it is possible that the performance and efficiency of such a system could be further improved.
In this project, two potential technologies were identified and thoroughly analysed. We are therefore able to say that the project objectives have been met and the project has proven worthwhile to the advancement of aerospace technology. Although these systems did not provide the desired results at this stage, they have shown the potential for improvement with further development.
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Leung, Chin Pui Perry. "Exhaust gas fuel reforming to achieve fuel saving." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4330/.
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As much as 70 to 75% of the energy in the fuel used by a car is turned into waste heat, with more than a third of this released through the exhaust pipe. Catalysis offers a way of recovering exhaust heat. By adding some of the fuel to a portion of the exhaust as it passes through a catalytic reactor, it is possible to produce a gas mixture with a higher heating value than the fuel. This strategy depends, however, on the catalytic reaction consuming heat, while generating readily-combustible products that can be fed back to the engine. An investigation into catalytic exhaust gas fuel reforming and its potential to improve engine emissions and efficiency when close-coupled to a spark ignition engine. Initial ethanol reforming reactions with simulated exhaust gas suggests that the desired reforming path, i.e. dry reforming, steam reforming and partial oxidation reforming reactions can raise the heating value of the input fuel (ethanol) by up to 120% providing exhaust gas temperatures are made available, with the highest being steam reforming > dry reforming > oxidative reforming. The undesired water gas shift reaction is inactive with this reforming catalyst, regardless of the reaction temperature and reactant ratios (e.g. O:C and H\(_2\)O:C). The characteristic of each reforming path is tentatively explained with deviations from the stoichiometry. Actual exhaust gas fuel reforming studies of gasoline is carried out at a range of exhaust gas temperatures. It was found that at exhaust gas temperature 600\(^0\) to 950\(^0\)C, the overall process efficiency ranges from 107 to 119%. By replacing 23.9% of gasoline fuel with simulated reformate, improvements in engine specific fuel consumption (SFC) and emissions (e.g. NOx, HC, CO2, CO) was achieved.
7
DeGolyer, Jessica Suzanne. "Fuel Life-Cycle Analysis of Hydrogen vs. Conventional Transportation Fuels." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-08192008-124223/.
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Fuel life-cycle analyses were performed to compare the affects of hydrogen on annual U.S. light-duty transportation emissions in future year 2030. Five scenarios were developed assuming a significant percentage of hydrogen fuel cell vehicles to compare different feedstock fuels and technologies to produce hydrogen. The five hydrogen scenarios are: Central Natural Gas, Central Coal Gasification, Central Thermochemical Nuclear, Distributed Natural Gas, and Distributed Electrolysis. The Basecase used to compare emissions was the Annual Energy Outlook 2006 Report that estimated vehicle and electricity mix in year 2030. A sixth scenario, High Hybrid, was included to compare vehicle technologies that currently exist to hydrogen fuel cell vehicles that commercially do not exist. All hydrogen scenarios assumed 30% of the U.S. light-duty fleet to be hydrogen fuel cell vehicles in year 2030. Energy, greenhouse emissions, and criteria pollutant emissions including volatile organic compounds, particulate matter, sulfur dioxides, nitrogen dioxides, and carbon monoxide were evaluated. Results show that the production of hydrogen using thermochemical nuclear technology is the most beneficial in terms of energy usage, greenhouse gas emissions, and criteria pollutant emissions. Energy usage decreased by 36%, greenhouse gas emissions decreased by 46% or 9.6 x 108 tons, and criteria emissions were reduced by 28-47%. The centrally-produced hydrogen scenarios proved to be more energy efficient and overall release fewer emissions than the distributed hydrogen production scenarios. The only hydrogen scenario to show an increase in urban pollution is the Distributed Natural Gas scenario with a 60% increase in SOx emissions..
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Lee, Won Yong Ph D. Massachusetts Institute of Technology. "Mathematical modeling of solid oxide fuel cells using hydrocarbon fuels." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74906.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references.
Solid oxide fuel cells (SOFCs) are high efficiency conversion devices that use hydrogen or light hydrocarbon (HC) fuels in stationary applications to produce quiet and clean power. While successful, HC-fueled SOFCs face several challenges, the most significant being performance degradation due to carbon deposition and the need of external reforming when using heavier HC. Modeling these devices faces these as well as other complexities such as the presence of multiple electrochemistry pathways including those of H2 and CO. The goals of this thesis are to: (1) improve the thermodynamic analysis of carbon deposition, (2) develop a multistep CO electrochemistry mechanism, and (3) apply the CO along with the H2 electrochemistry mechanisms to predict the cell performance when using syngas. Two carbon deposition mechanisms have been identified: homogeneously formed soot and catalytically grown carbon fiber. All previous thermodynamic analyses have used graphite to represent the properties of the deposited carbon regardless of the formation mechanism. However, the energetic and entropic properties of these two types of carbon are different from those of graphite. A new thermodynamic analysis is proposed that: (1) uses experimentally measured data for carbon fiber if the anode includes Ni catalyst; and (2) uses soot precursors such as CH3 and C2H2 to predict soot formation. The new approach improves the prediction of the onset of carbon deposition where previous analyses failed. A new multi-step CO electrochemistry model is proposed in which CO is directly involved in the charge-transfer steps. The model structure, with a single set of kinetic parameters at each temperature, succeeds in reproducing the characteristics of the EIS data of patterned anodes including the inductive loop at high activation overpotential. The model successfully predicts the steady-state Tafel plots, and explains the positive dependence of the exchange current density on Pco2 - Finally, a membrane-electrode-assembly (MEA) model is developed incorporating multispecies transport through the porous structure, detailed elementary heterogeneous reactions on the Ni surface, and for the first time, detailed electrochemistry models for H2 and CO. The model successfully reproduces the performance of SOFCs using pure H2 or CO. The MEA model can isolate/distinguish between the roles/contributions of the reforming chemistry and CO electrochemistry in SOFCs using syngas. Adding reforming thermochemistry improves the agreement with experiments at lower current densities, and raises the limiting current density by providing more H2 via the water-gas shift reaction. Adding CO electrochemistry improves the prediction at high current densities by the additional current generated by the CO electrochemical oxidation. The current from CO becomes comparable to that from H2 as the CO content at the TPB increases.
by Won Yong Lee.
Ph.D.
9
Lively, Treise. "Ethanol fuel cell electrocatalysis : novel catalyst preparation, characterization and performance towards ethanol electrooxidation." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602560.
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Matter, Paul H. "Electrocatalytic and fuel processing studies for portable fuel cells." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1149037376.
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Salih, Fawzi Mohamed. "Automotive fuel economy measures and fuel usage in Sudan." Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293763.
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Aquien, Alexandre. "Fuel cycle options for optimized recycling of nuclear fuel." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/42340.
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Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.Page 200 blank.
Includes bibliographical references (p. 170-171).
The accumulation of transuranic inventories in spent nuclear fuel depends on both deployment of advanced reactors that can be loaded with recycled transuranics (TRU), and on availability of the facilities that separate and reprocess spent fuel. Three recycling strategies are explored in this study: (1) Recycling in thermal Light 'Water Reactors (LWR) using CONFU technology (COmbined Non-Fertile and UO2 fuel), (2) recycling of TRU in fast cores of Actinide Burner Reactors (ABR), and (3) recycling of TRU with UO2 in self-sustaining Gas-cooled Fast Reactors (GFR). Choosing one fuel cycle strategy over the others involves trade-offs that need to be quantified. The CONFU, ABR, and GFR strategies differ from each other in terms of TRU loading in the reactor, net TRU incineration, capacities of recycling facilities needed, technology option availability, and flexibility. The CONFU and GFR are assumed to achieve zero net TRU incineration, while the ABR is a net consumer of TRU. The TRU loading is greatest in GFR and lowest in CONFU. While both CONFU and ABR require separation (of TRU from U) and reprocessing (recycling of TRUs from fertile-free fuel), the GFR is designed to, in equilibrium, recycle TRU+U after extraction of fission products only. It is assumed that thermal recycling is available in the short-term (2015), as opposed to recycling in fast reactors (2040). Finally, thermal recycling is the most flexible as either CONFU batches or regular LWR uranium batches can be loaded; the issue of running out of TRU fuel is therefore irrelevant for this option. A fuel cycle simulation tool, CAFCA II - Code for Advanced Fuel Cycles Assessment - has been developed. The CAFCA II code tracks the mass distribution of TRU in the system and the cost of all operations.
(cont.) The code includes a specific model for recycling plants deployment; as an industrial process occurring in facilities with given capacities and investment requirements. These facilities may operate with a minimum target capacity factor during the lifetime of the plant. The deployment of these facilities is also constrained by a user-specified ability to add recycling capacity within a given time interval. Finally, the CAFCA II code includes a specific model for recycling prices as a function of plants nominal capacities, which reflects the economies of scale that go with increasing the nominal capacity of recycling plants. Our first case-study identifies the optimal choice of fuel cycle option and recycling plants capacities as a function of the deployment of advanced fuel cycle technologies over the next hundred years and under the assumption of the US demand for nuclear energy growing at a 2.4% annual rate. Key figures of merit for comparison of the strategies are the reduction of TRU interim storage requirements, the maximization of TRU incineration, the minimization of the size of the fleets of recycling plants and fast reactors, and the fuel cycle cost. We found that it is not possible to minimize simultaneously (1) the construction rate of advanced reactors and advanced spent fuel recycling facilities, and (2) the construction rate of U02 spent fuel separation facilities. The latter was found to be more constraining than the first for purposes of TRU inventories reduction. We found also that reactor technologies with zero net TRU destruction rate can achieve total depletion of TRU inventories is spent fuel interim storage at a lower fuel cycle cost and with fewer recycling facilities than reactor technologies that incinerate TRU; the lower fuel cycle cost is achieved at the expense of a lesser reduction of total TRU inventories.
(cont.) Finally, we found that, if the construction rate of advanced nuclear technologies is large enough, the later introduction date of fast recycling schemes compared to thermal recycling schemes is not discriminatory, with regards to the reduction of TRU inventories in interim storage by 2100. The potential of multi-lateral approaches to the nuclear fuel cycle has recently been widely acknowledged. Cited benefits include cost attractiveness following from economies of scale, proliferation resistance and collaborative and more efficient nuclear waste treatment strategy. CAFCA II has been developed to quantify these trade implications for the back-end of the fuel cycle Three bi-lateral scenarios of partnerships have been examined between two regions: first a scenario where the "Fuel-leasing/fuel take-back" concept is implemented, second a scenario with "Limited Collaboration" at the back-end fuel cycle, where spent fuel recycling and advanced fuel fabrication are externalized in countries that have these technologies, and third a scenario of "Full Collaboration", under which two regions fully collaborate at the fuel cycle back-end: spent fuel inventories and advanced fuel cycle facilities are co-owned and comanaged. Our second case-study concentrates on optimizing the choice of (1) fuel cycle option, (2) spent fuel recycling plant capacities, and (3) partnership scenario by analyzing the implications of these choices for the LWR-CONFU, LWR/ABR, and LWR/GFR strategies. The nuclear fuel cycle is simulated in a two-region context from 2005 to 2100 under the assumption that one region represents the US growing at a 2.4% annual rate and the other region represents Brazil, Indonesia, and Mexico growing at a 7.4% annual rate until 2080, and at 2.4% afterwards.
(cont.) We found that a US partnership with Brazil, Mexico, and Indonesia, could be advantageous to the reduction of TRU storage in both regions if the construction rate of UO2 spent fuel separation plants would be larger than one 1,000 MT/yr plant every two years after 2050. We found also that, from the point of view of the spent fuel recycling industry, use of largest recycling plants with the lowest construction cost per unit of installed capacity becomes optimal only with multi-national approaches to the fuel cycle back-end.
by Alexandre Aquien.
S.M.
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Flora, Giacomo. "Fuel Structure Effects on Surrogate Alternative Jet Fuel Emission." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1450286398.
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Sinuka, Yonwaba. "Performance testing of a diesel engine running on varying blends of jatropha oil, waste cooking oil and diesel fuel." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2436.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016.The high cost of fossil fuels and the fact that the world has arguably reached its peak oil production, has driven the need to seek alternative fuel sources. The main objective of the current study is to determine the performance of a laboratory-mounted diesel engine when fuelled with varying laboratory prepared biofuel and biodiesel and whether the advancement of the injection timing parameters will improve the engine power output and improve the smoke effect of these different fuel blends. The laboratory prepared biofuels used in this project range from 100% bio-fuel (BF100) to 50%, 30% and 10% biodiesel blends (BF50, BF30 and BF10, respectively). It should be noted that these blends are not commercially available, since they were blended in the laboratory specifically for these tests. The overall results of the study show that there is a distinct opportunity for using certain bio-fuel blends in specific applications as the power outputs are no more than one quarter less than that of base diesel. Concomitantly, the smoke opacity in all of the blends is lower than that of base diesel, which is a significant benefit in terms of their overall air emissions.
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Rohaly, Matthew Joseph. "Decomposition of Aromatic Amines in a Jet Fuel Surrogate." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1417777531.
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Huang, Lloyd Michael. "Analysis of multi-recycle thorium fuel cycles in comparison with once-through fuel cycles." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47662.
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The purpose of this research is to develop a methodology for a thorium fuel recycling analysis that provides results for isotopics and radio-toxicity evaluation and analysis. This research is motivated by the need to reduce the long term radiological hazard in spent nuclear fuel, which mitigates the mixing hazard (radiotoxicity and chemical toxicity) and decay heat load on the repository. The first part of the thesis presents comparison of several once-through cases with uranium and thorium fuels to show how transuranics build up as fuel is depleted. The once-through analysis is performed for the following pairs of comparison cases: low enriched uranium dioxide (UOX) vs. thorium dioxide with 233UOX (233U-ThOX), natural uranium dioxide mixed with transuranic oxides (U-TRUOX) vs. thorium dioxide mixed with transuranic oxides (Th-TRUOX), natural uranium dioxide mixed with weapons grade plutonium dioxide (U-WGPuOX) vs. thorium dioxide mixed with weapons grade plutonium dioxide (Th-WGPuOX), natural uranium dioxide mixed with reactor grade plutonium dioxide (U-RGPuOX) vs. thorium mixed with reactor grade plutonium dioxide (Th-RGPuOX). The second part of the research evaluates the thorium fuel equilibrium cycle in a pressurized water reactor (PWR) and compares several recycling cases with different partitioning schemes. Radio-toxicity results of the once-through cycle and multi-recycle calculations demonstrate advantages for thorium fuel and reprocessing with respect to long term nuclear waste management.
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Marquez, Matias G. "Silicide fuel swelling behavior and its performance in I2S-LWR." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53970.
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The swelling mechanisms of U3Si2 under neutron irradiation in reactor conditions are not unequivocally known. The limited experimental evidence that is available suggests that the main driver of the swelling in this material would be fission gases accumulation at crystalline grain boundaries. The steps that lead to the accumulation of fission gases at these locations are multiple and complex. However, gradually, the gaseous fission products migrate by diffusion. Upon reaching a grain boundary, which acts as a trap, the gaseous fission products start to accumulate, thus leading to formation of bubbles and hence to swelling. Therefore, a quantitative model of swelling requires the incorporation of phenomena that increase the presence of grain boundaries and decrease grain sizes, thus creating sites for bubble formation and growth. It is assumed that grain boundary formation results from the conversion of stored energy from accumulated dislocations into energy for the formation of new grain boundaries.This thesis attempts to develop a quantitative model for grain subdivision in U3Si2 based on the above mentioned phenomena to verify the presence of this mechanism and to use in conjunction with swelling codes to evaluate the total swelling of the pellet in the reactor during its lifetime.
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ROMANATO, LUIZ S. "Estudo de um casco nacional e sua instalacao para armazenagem seca de combustivel nuclear queimado gerado em reatores PWR." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9476.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Chandler, Sharon (Jess) Ann. "Comparison of Reprocessing Methods for Light Water Reactor Fuel." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14018.
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Currently, the United States is investigating methods to close the nuclear fuel cycle
and increase the use of nuclear power for electricity and cogeneration applications. Congress has called for and held hearings in an attempt to determine an appropriate path forward for reprocessing of nuclear fuel. However, each current proposed method presents a different
set of attributes with regards to: Complexity, safety, wastes, and proliferation risks.
This thesis provides a decision analysis methodology for approaching the reprocessing
issue. The presented methodology builds on the previous work done in the 1970s. Further,
current reprocessing technologies which are capable of processing the oxide fuels utilized
in the majority of United States reactors are evaluated across ten attributes related to
reprocessing performance. A weighted total score is provided for each reprocessing method
in order to separate the technological from political or emotional issues related to selection of a process.
While it is not the goal of this thesis to select a particular best technology, application of this methodology results in the selection of the COmbined EXtraction (COEX) technology when equal weighting is put on the attributes as defined. It is unlikely that a decision maker will approach this decision with equal weighting; however, actual decision maker weightings are known only to the decision makers. By altering the weightings, different technologies are selected.
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Sukjit, Ekarong. "Synergistic effects of alcohol-based renewable fuels : fuel properties and emissions." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4674/.
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Biodiesel is known to improve the fuel properties of alcohol-diesel blends. However biodiesel is obtained from different feedstock and consequently the composition can be different, with varying fatty acid profiles resulting in different physical and chemical properties and a different response when blended with alcohol-diesel blends. To understand the effect of molecular structure of biodiesel on fuel properties and emissions, the most representative individual fatty acid methyl esters were added to alcohol-diesel blends. The results show that 15% of all methyl esters was enough to avoid phase separation of alcohol-diesel blends and keep the wear scar diameter of the blends below the limitation required by lubricity standards. Short carbon chain length and saturated methyl ester are recommended to improve emissions of alcohol-diesel blends. A comparison between two different alcohols used in the engine tests highlighted that butanol blends were more effective in reducing carbonaceous gas emissions and particulate matter emissions than ethanol blends. Further research on the effect of molecular structure of biodiesel on alcohol-diesel blends was conducted to understand influence of hydroxylated biodiesel which is derived from castor oil. The existence of hydroxyl group in biodiesel considerably improves the lubricity of alcohol-diesel blends. It was also shown to be beneficial in terms of engine-out emissions such as enhancing soot oxidation and reducing activation energy to oxidise soot emissions. To counteract the likely increase in gaseous carbonaceous emissions with alcohol blends, the addition of hydrogen to replace part of the carbon within the liquid fuel was studied. The incorporation of hydrogen and alcohol blends indicates that there was a dramatic reduction in carbon dioxide, unburnt hydrocarbons and particulate matter emissions.
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Mirzababaei, Jelvehnaz. "Solid Oxide Fuel Cells with Methane and Fe/Ti Oxide Fuels." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1415461807.
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Stutz, Michael Jun. "Hydrocarbon fuel processing of micro solid oxide fuel cell systems." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17455.
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Gerber, Chad A., and Jeremy A. Clark. "More fightless-fuel: reducing fuel burn through ground process improvement." Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34667.
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Approved for public release; distribution is unlimitedAligning fiscal policies with energy conservation initiatives and operational requirements is vital to achieving a positive and sustainable energy outlook for the United States Navy. The purpose of this study is to fill critical gaps in current military aviation energy conservation research. To date, such research has failed to incentivize and reward individual aviation squadrons to conserve. Commercial aviation uses collaborative decision-making (CDM) tools to minimize costs associated with aircraft delays. Embracing a lean approach to operational management, the commercial sector has refined communications between air carriers, airport operators, ground handlers, and air traffic control. This study suggests applying commercial CDM frameworks to all of Naval Aviation to increase efficiency and operational effectiveness. Specific analysis includes the impact of ground resource capacity management, airfield demand analysis (slot arrival system) and demand management cost analysis on F/A-18 Hornet squadrons.
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Nabity, James Allen. "Metallized fuel particle size study in a solid fuel ramjet." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26063.
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Reese, Drew A. (Drew Amelia). "Dependence of transuranic content in spent fuel on fuel burnup." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41692.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.Includes bibliographical references (p. 33).
As the increasing demand for nuclear energy results in larger spent fuel volume, implementation of longer fuel cycles incorporating higher burnup are becoming common. Understanding the effect of higher burnup on the spent fuel composition and radioactive properties is essential to ensure that spent fuel receives proper cooling in storage before it is sent to a disposal site or proper treatment and reprocessing if its useful content is to be extracted prior to disposal. Using CASMO-4, a standard Westinghouse 4-loop pressurized water reactor model was created and simulated with a three batch fuel cycle. U-235 enrichment was adjusted to achieve fuel burnups of 30, 50, 70 and 100 MWD per kg of initial uranium. These burnups demanded reload enrichments of 3.15%, 4.63%, 6.26% and 9.01% U-235 w/o respectively. The resultant spent fuel transuranic isotopic compositions were then provided as input into ORIGEN to study the decay behavior of the spent fuel. It was found that when burnup increased from 30 MWD/kg to 100 MWD/kg, the activity more than doubled due to the decreased Pu-241 content and the increased Np-239 presence. More importantly, the activity per MWD significantly decreased despite absolute increases in unit mass. The net result is that the half-life of high burnup fuels is greatly increased in comparison to low burnup fuels for the first decade of life. Beginning from day 14 after shutdown and until 10 years later, the 100 MWD/kg fuel has a half-life of 129 days while the 30 MWD/kg spent fuel has a half life of 5 days. Previous work has suggested that different trends dominate decay behavior from years 10 to 100 years following discharge.
by Drew A. Reese.
S.B.
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Zino, John Frederick. "Analysis of subcritical experiments using fresh and spent research reactor fuel assemblies." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/17507.
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Chen, Guoqiang. "Fuel volatility modeling." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12282.
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Gutiérrez, Daniel. "Green Fuel Simulations." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79244.
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Many industries have entered a new global phase which takes the environment in mind. The gas turbine industry is no exception, where the utilization of green fuels is the future to spare the environment from carbon dioxide and NOx emissions. Hydrogen has been identified as a fuel which can fulfil the global requirements set by governments worldwide. Combustion instabilities are not inevitable during gas turbine operations, especially when using a highly reactive and diffusive fuel as hydrogen. These thermoacoustics instabilities can damage mechanical components and have economic consequences in terms of maintenance and reparation. Understanding these thermoacoustic instabilities in gas turbine burners is of great interest. COMSOL Multiphysics offers a robust acoustic module compared to other available acoustic simulation programs. In this thesis, an Acoustic finite element model was built representing an atmospheric combustion rig (ACR), used to test the burners performance and NOx emissions. Complementary computational fluid dynamics (CFD) simulations were performed for 100 % hydrogen as fuel by using the Reynolds average Navier-Stokes (RANS) lag EB k - epsilon turbulence model. Necessary data was successfully imported to the Acoustic finite element model. Different techniques of building the mesh were used in COMSOL Multiphysics and NX. Similar results were obtained, proving that both mesh tools work well in acoustic simulations. Two different ways of solving the eigenvalue problem in acoustics were implemented, the classic Helmholtz equation and Linearized Navier-Stokes equations, both in the frequency domain. The Helmholtz equation proved to be efficient and detected multiple modes in the frequency range of interest. Critical modes which lived in the burner and the combustion chamber were identified. Defining a hard and soft wall boundary condition at the inlets and outlet of the atmospheric combustion rig gave similar eigenfrequencies when comparing the two boundary conditions. The soft wall boundary condition was defined with a characteristic impedance, giving a high uncertainty whether the results were trustworthy or not. A boundary condition study revealed that the boundary condition at the outlet was valid for modes living in the burner and combustion chamber. Solving the eigenvalue problem with the Linearized Navier-Stokes equations proved to be computationally demanding compared to the Helmholtz equation. Similar modes shapes were found at higher frequencies, but pressure perturbations were observed in the region where the turbulence was dominant. A prestudy for a stability analysis was established, where the ACR and the flame was represented as a generic model. Implementing a Flame Transfer Function (FTF), more specifically a linear n - tau model, showed that the time delay tau is most sensible for a parametric change and hence needs to be chosen cautiously
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Pinto, Maria Jorge Pratas de Melo. "Biodiesel fuel formulation." Doctoral thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/9328.
Full textAbstract:
Doutoramento em Engenharia QuímicaO consumo de energia a nível mundial aumenta a cada dia, de forma inversa aos recursos fósseis que decrescem de dia para dia. O sector dos transportes é o maior consumidor deste recurso. Face ao actual cenário urge encontrar uma solução renovável e sustentável que permita não só, diminuir a nossa dependência de combustíveis fósseis mas fundamentalmente promover a sua substituição por energias de fontes renováveis. O biodiesel apresenta-se na vanguarda das alternativas aos combustiveis derivados do petróleo, para o sector dos transportes, sendo considerado uma importante opção a curto prazo, uma vez que o seu preço pode ser competitivo com o diesel convencional, e para a sua utilização o motor de combustão não necessita de alterações. O biodiesel é uma mistura líquida, não tóxica, biodegradável de ésteres de ácidos gordos, sem teor de enxofre ou compostos aromáticos, apresenta boa lubricidade, alto número de cetano, e origina emissões gasosas mais limpas. O presente trabalho contribui para um melhor conhecimento da dependência das propriedades termofisicas do biodiesel com a sua composição. A publicação de novos dados permitirá o desenvolvimento de modelos mais fiáveis na previsão do comportamento do biodiesel. As propriedades densidade e viscosidade são o espelho da composição do biodiesel, uma vez que dependem directamente da matéria prima que lhe deu origem, mais do que do processo de produção. Neste trabalho os dados medidos de densidade e viscosidade de biodiesel foram testados com vários modelos e inclusivamente foram propostos novos modelos ajustados para esta família de compostos. Os dados medidos abrangem uma ampla gama de temperaturas e no caso da densidade também foram medidos dados a alta pressão de biodiesel e de alguns ésteres metilico puros. Neste trabalho também são apresentados dados experimentais para o equilíbrio de fases sólido-liquído de biodiesel e equlibrio de fases líquidolíquido de alguns sistemas importantes para a produção de biodiesel. Ambos os tipos de equilíbrio foram descritos por modelos desenvolvidos no nosso laboratório. Uma importância especial é dado aqui a propriedades que dependem do perfil de ácidos gordos da matéria-prima além de densidade e viscosidade; o índice de iodo e temperature limite de filtrabalidade são aqui avaliados com base nas considerações das normas. Os ácidos gordos livres são um sub-produto de refinação de óleo alimentar, que são removidos na desodoração, no processo de purificação do óleo. A catálise enzimática é aqui abordada como alternativa para a conversão destes ácidos gordos livres em biodiesel. Estudou-se a capacidade da lipase da Candida antartica (Novozym 435) para promover a esterificação de ácidos gordos livres com metanol ou etanol, utilizando metodologia de superfície de resposta com planeamento experimental. Avaliou-se a influência de diversas variáveis no rendimento da reacção.
World energy consumption rises every day and, inversely, fossil fuel resources are dwindling day by day. Transportation sector is the bigger consumer of oil. Faced with the actual scenario a renewable and sustenable alternative is needed, not just to decrease our dependence of petroleum but also to base our power in a renewable source. Biodiesel is at the forefront of the alternatives to petroleum based fuels in the transportation sector, being considered an important short-time option since its price can be competitive with conventional diesel and no motor changes are required. Biodiesel consists on a liquid blend of, non toxic, biodegradable fatty acid esters, with non sulfur and aromatic content, good lubricity, high cetane number, nontoxic character of their exhaust emissions and cleaner burning. Aiming at tuning biodiesel to optimize the fuel composition, the present work contributes for a better knowledge of de depencende of thermophysical properties of biodiesel on their compositon. New data is required to help in the development of reliable models to predict biodiesel behavior. Density and viscosity data are a mirror of biodiesel composition, as both depend on the raw material, more than the production process. New data of density and viscosity were measured and respective models were tested and compared, and new adjusted parameters proposed for this family of compounds. The measured data include a wide range of temperatures and in the case of density data were also measured at high pressure for biodiesel and some pure methyl esters. This work also reports experimental data for the solid-liquid-phase equilibria of biodiesel and, liquid-liquid equilibria of some important systems in biodiesel production. Both type of equilibria were described with models developed in our laboratory. A special importance is here given to properties that depend on fatty acid profile of raw material besides density and viscosity; the iodine value, and cold filter plugging point are here evaluated based on norm considerations. Free Fatty Acids (FFA) are a by-product in edible oil refining, that are removed in the deodorizing step on oil purification. Enzymatic catalysis is here studied as an alternative to convert this by-product into biodiesel. The ability of immobilized lipase from Candida antartica (Novozym 435) to catalize the esterification of FFA with methanol and ethanol were evaluated using response surface methodology with an experimental design. Influence of several variables were evaluated in the yield of reaction.
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Lim, Keng Guan. "Microfluidic fuel cell." View abstract/electronic edition; access limited to Brown University users, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3319104.
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Murray, K. D. "Biochemical fuel cells." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380401.
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Lang, Kevin R. 1980. "Effect of fuel properties on the first cycle fuel delivery in a Port Fuel Injected Spark Ignition Engine." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27074.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 73-74).
Achieving robust combustion while also yielding low hydrocarbon (HC) emissions is difficult for the first cycle of cranking during the cold start of a Port Fuel Injected (PFI) Spark Ignition (SI) engine. Cold intake port wall and valve temperatures, near-atmospheric manifold pressure, and low port air velocity combine to create an adverse environment for fuel delivery - the process of injecting and vaporizing liquid fuel to create a combustible air-fuel mixture. As a result, only a small fraction of the injected fuel mass contributes to the combustible mixture; the fraction is less than 10% at cold ambient temperatures. With fast light off catalysts, the first cycle produces a significant portion of the total trip emissions. The low fuel delivery fraction results in high residual liquid fuel in both the port and cylinder; this fuel contributes significantly to the exhaust HC emissions. Since the first cycle engine control is open-loop, the Engine Control Unit (ECU) must determine how much fuel to inject under given conditions - temperature, pressure, and for a given fuel. Fuel properties play a significant role in first cycle fuel delivery, since the energy available for vaporization is a limiting factor in fuel delivery. The effect of fuel properties on fuel delivery for the first cycle was quantified at a wide range of cold start temperatures by using a skip-firing strategy to simulate the first cycle of cranking on a production PFI engine. Four fuels between 1083 and 1257 Driveability Index (DI) were tested, and the fuel delivery results have been correlated to properties of the ASTM distillation curve. The fractional distillation point that correlates to fuel delivery is a function of temperature - at colder temperatures, the results
(cont.) correlate with the more volatile end of the distillation curve. Fuel delivery results for the fuels were also simulated with a thermodynamics-based fuel delivery model based on partial equilibrium with the charge air.
by Kevin R. Lang.
S.M.
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Reece, Warren Daniel. "Theory of cladding breach location and size determination using delayed neutron signals /." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/13317.
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PESSOA, JOAO S. "Projeto piloto do etanol - PPE. Alternativa energetica para substituicao parcial ou total do oleo combustivel em plantas de geracao termoeletrica." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11185.
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Made available in DSpace on 2014-10-09T12:49:17Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:01:41Z (GMT). No. of bitstreams: 1 09996.pdf: 9839112 bytes, checksum: 191077eddeaa1bbd2d98314d2e7d250a (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Sommer, Christopher Michael. "Subcritical transmutation of spent nuclear fuel." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41205.
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A series of fuel cycle simulations were performed using CEA's reactor physics code ERANOS 2.0 to analyze the transmutation performance of the Subcritical Advanced Burner Reactor (SABR). SABR is a fusion-fission hybrid reactor that combines the leading sodium cooled fast reactor technology with the leading tokamak plasma technology based on ITER physics. Two general fuel cycles were considered for the SABR system. The first fuel cycle is one in which all of the transuranics from light water reactors are burned in SABR. The second fuel cycle is a minor actinide burning fuel cycle in which all of the minor actinides and some of the plutonium produced in light water reactors are burned in SABR, with the excess plutonium being set aside for starting up fast reactors in the future. The minor actinide burning fuel cycle is being considered in European Scenario Studies. The fuel cycles were evaluated on the basis of TRU/MA transmutation rate, power profile, accumulated radiation damage, and decay heat to the repository. Each of the fuel cycles are compared against each other, and the minor actinide burning fuel cycles are compared against the EFIT transmutation system, and a low conversion ratio fast reactor.
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Chen, Eric L. "Testing and modelling of a fuel cell and a fuel processor." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394009.
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Cuseo, James M. (James Michael). "Cold start fuel management of port-fuel-injected internal combustion engines." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32380.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 64).
The purpose of this study is to investigate how changes in fueling strategy in the second cycle of engine operation influence the delivered charge fuel mass and engine out hydrocarbon (EOHC) emissions in that and subsequent cycles. Close attention will be paid to cycle-to-cycle interaction of the fueling strategy. It is our intent to see if residual fuel from each cycle has a predicable influence on subsequent cycle's charge mass and EOHC emissions. The fast flame ionization detector is employed to measure both in-cylinder and engine out hydrocarbon concentrations for various cold start strategies. The manufacturer's original fueling strategy is used as a starting point and is compared to a "in-cylinder fuel air ratio (Phi) [approx.] 1" case (a fueling strategy that results in an in-cylinder concentration of approximately stoichiometric for each of the first five cycles) and to a number of cases that are chosen to illustrate cycle-to-cycle mixture preparation dependence on second cycle fueling. Significant cycle-to-cycle dependence is observed with the change in second cycle. A fueling deficit in cycle two has a more pronounce effect on future cycles delivered charge mass than a fueling surplus while a fueling surplus in cycle two has a more pronounce effect on future cycles charge mass than a fueling deficit.
by James M. Cuseo.
S.M.
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Saxe, Maria. "Bringing fuel cells to reality and reality to fuel cells : A systems perspective on the use of fuel cells." Doctoral thesis, KTH, Energiprocesser, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9192.
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With growing awareness of global warming and fear of political instability caused by oil depletion, the need for a society with a sustainable energy system has been brought to the fore. A promising technology often mentioned as a key component in such a system is the fuel cell technology, i.e. the energy conversion technology in focus in this thesis. The hopes and expectations on fuel cells are high and sometimes unrealistically positive. However, as an emerging technology, much remains to be proven and the proper use of the technology in terms of suitable applications, integration with society and extent of use is still under debate. This thesis is a contribution to the debate, presenting results from two fuel cell demonstration projects, looking into the introduction of fuel cells on the market, discussing the prospects and concerns for the near-term future and commenting on the potential use in a future sustainable energy system. Bringing fuel cells to reality implies finding near-term niche applications and markets where fuel cell systems may be competitive. In a sense fuel cells are already a reality as they have been demonstrated in various applications world-wide. However, in many of the envisioned applications fuel cells are far from being competitive and sometimes also the environmental benefit of using fuel cells in a given application may be questioned. Bringing reality to fuel cells implies emphasising the need for realistic expectations and pointing out that the first markets have to be based on the currently available technology and not the visions of what fuel cells could be in the future. The results from the demonstration projects show that further development and research on especially the durability for fuel cell systems is crucial and a general recommendation is to design the systems for high reliability and durability rather than striving towards higher energy efficiencies. When reliability and durability are achieved fuel cell systems may be introduced in niche markets where the added values presented by the technology compensate for the initial high cost.QC 20100909
Energy Systems Programme
Clean Urban Transport for Europe
GlashusEtt
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Vittilapuram, Subramanian Kannan. "Modelin combustion of multicomponent fuel droplets: formulation and application to transportation fuels." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3320.
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The quasi-steady, spherically symmetric combustion of multicomponent isolated fuel
droplets has been modeled using modified Shvab-Zeldovich variable mechanism. Newly
developed modified Shvab-Zeldovich equations have been used to describe the gas phase
reactions. Vapor-liquid equilibrium model has been applied to describe the phase change at the
droplet surface. Constant gas phase specific heats are assumed. The liquid phase is assumed to
be of uniform composition and temperature. Radiative heat transfer between the droplet and
surroundings is neglected.
The results of evaporation of gasoline with discrete composition of hydrocarbons have been
presented. The evaporation rates seem to follow the pattern of volatility differentials. The
evaporation rate constant was obtained as 0.344mm2/sec which compared well with the unsteady
results of Reitz et al. The total evaporation time of the droplet at an ambience of 1000K was
estimated to be around 0.63 seconds. Next, the results of evaporation of representative diesel
fuels have been compared with previously reported experimental data. The previous experiments
showed sufficient liquid phase diffusional resistance in the droplet. Numerical results are
consistent with the qualitative behavior of the experiments. The quantitative deviation during the
vaporization process can be attributed to the diffusion time inside the droplet which is
unaccounted for in the model. Transient evaporation results have also been presented for the
representative diesel droplets. The droplet temperature profile indicates that the droplet
temperature does not reach an instantaneous steady state as in the case of single-component
evaporation.
To perform similar combustion calculations for multicomponent fuel droplets, no simple
model existed prior to this work. Accordingly, a new simplified approximate mechanism for
multicomponent combustion of fuel droplets has been developed and validated against several
independent data sets. The new mechanism is simple enough to be used for computational
studies of multicomponent droplets.
The new modified Shvab-Zeldovich mechanism for multicomponent droplet combustion has
been used to model the combustion characteristics of a binary alcohol-alkane droplet and
validated against experimental data. Burn rate for the binary droplet of octanol-undecane was
estimated to be 1.17mm2/sec in good concurrence with the experimental value of 0.952mm2/sec
obtained by Law and Law. The model has then been used to evaluate the combustion
characteristics of diesel fuels assuming only gas phase reactions. Flame sheet approximation has
been invoked in the formulation of the model.
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Farao, Javon. "Toward a full aircraft model platform for fuel slosh-structure interaction simulations." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/24315.
Full textAbstract:
The purpose of this study was to initiate the development of a full aircraft model (FAM) for the purpose of non-linear loads calculation of an aircraft. The FAM is employed during the design process of an aircraft and comprises of various reduced-order models (ROMs). These are mainly structural, slosh and aerodynamic loads. This study focused on the structural and slosh aspects using Ele- mental(TM) software as the base. First, a structural ROM was developed such that it is compatible with Airbus data and processes. The developed code reads in MSC Nastran data, from which Hermitian finite element discretisation is performed followed by transient calculations. To this end, the structure was represented by Timoshenko beam theory. The structural ROM was validated and verified against the widely used MSC Nastran commercial software. Simulated dynamic responses were within 5% while eigenvalue predictions were within 2% of each other. Secondly, a strongly-coupled partitioned fluid-structure interaction (FSI) scheme was deployed to incorporate the high-fidelity sloshing fluid onto the structure. Lastly, the developed FSI technology was verified and validated against challenging analytical as well as real-world benchmark test cases. It was demonstrated to be accurate and robust in all cases.
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Abdullah, Hanisom binti. "High energy density fuels derived from mallee biomass: fuel properties and implications." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/2259.
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Mallee biomass is considered to be a second-generation renewable feedstock in Australia and will play an important role in bioenergy development in Australia. Its production is of large-scale, low cost, small carbon footprint and high energy efficiency. However, biomass as a direct fuel is widely dispersed, bulky, fibrous and of high moisture content and low energy density. High logistic cost, poor grindability and mismatch of fuel property with coal are some of the key issues that impede biomass utilisation for power generation. Therefore, innovations are in urgent need to improve biomass volumetric energy densification, grindability and good fuel matching if co-fired with coal. Biomass pyrolysis is a flexible and low-cost approach that can be deployed for this purpose. Via pyrolysis, the bulky biomass can be converted to biomass-derived high-energy-density fuels such as biochar and/or bio-oil. So far there has been a lack of fundamental understanding of mallee biomass pyrolysis and properties of the fuel products.The series of study in this PhD thesis aims to investigate the production of such high-energy- density fuels obtained from mallee pyrolysis and to obtain some new knowledge on properties of the resultant fuels and their implications to practical applications. Particularly, the research has been designed and carried out to use pyrolysis as a pretreatment technology for the production of biochar, bio-oil and bioslurry fuels. The main outcomes of this study are summarised as follows.Firstly, biochars were produced from the pyrolysis of centimetre-sized particles of mallee wood at 300-500°C using a fixed-bed reactor under slow-heating conditions. The data show that at pyrolysis temperatures > 320°C, biochar as a fuel has similar fuel H/C and O/C ratios compared to Collie coal which is the only coal being mined in WA. Converting biomass to biochar leads to a substantial increase in fuel mass energy density from ~10 GJ/tonne of green biomass to ~28 GJ/tonne of biochars prepared from pyrolysis at 320°C, in comparison to 26 GJ/tonne for Collie coal. However, there is little improvement in fuel volumetric energy density, which is still around 7-9 GJ/m[superscript]3 in comparison to 17 GJ/m[superscript]3 of Collie coal. Biochars are still bulky and grinding is required for volumetric energy densification. Biochar grindability experiments have shown that the fuel grindability increases drastically even at pyrolysis temperature as low as 300°C. Further increase in pyrolysis temperature to 500°C leads to only small increase in biochar grindability. Under the grinding conditions, a significant size reduction (34-66 % cumulative volumetric size <75 μm) of biochars can be achieved within 4 minutes grinding (in comparison to only 19% for biomass after 15 minutes grinding), leading to a significant increase in volumetric energy density (e.g. from ~8 to ~19 GJ/m[superscript]3 for biochar prepared from pyrolysis at 400°C). Whereas grinding raw biomass typically result in large and fibrous particles, grinding biochar produce short and round particles highly favourable for fuel applications.Secondly, it is found that the pyrolysis of different biomass components produced biochars with distinct characteristics, largely because of the differences in the biological structure of these components. Leaf biochars showed the poorest grindability due to the presence of abundant tough oil glands in leaf. Even for the biochar prepared from the pyrolysis of leaf at 800°C, the oil gland enclosures remained largely intact after grinding. Biochars produced from leaf, bark and wood components also have significant differences in ash properties. Even with low ash content, wood biochars have low Si/K and Ca/K ratios, suggesting these biochars may have a high slagging propensity in comparison to bark and leaf biochars.Thirdly, bio-oil and biochar were also produced from pyrolysis of micron-size wood particle using a fluidised-bed reactor system under fast-heating conditions. The excellent grindability of biochar had enabled desirable particle size reduction of biochar into fine particles which can be suspended into bio-oil for the preparation of bioslurry fuels. The data have demonstrated that bioslurry fuels have desired fuel and rheological characteristics that met the requirements for combustion and gasification applications. Depending on biochar loading, the volumetric energy density of bioslurry is up to 23.2 GJ/m[superscript]3, achieving a significant energy densification (by a factor > 4) in comparison to green wood chips. Bioslurry fuels with high biochar concentrations (11-20 wt%) showed non-Newtonian characteristics with pseudoplastic behaviour. The flow behaviour index, n decreases with the increasing of biochar concentration. Bioslurry with higher biochar concentrations has also demonstrated thixotropic behaviour. The bioslurry fuels also have low viscosity (<453 mPa.s) and are pumpable at both room and elevated temperatures. The concentrations of Ca, K, N and S in bioslurry are below the limits of slurry fuel guidelines.Fourthly, bio-oil is extracted using biodiesel to produce two fractions, a biodiesel-rich fraction (also referred as bio-oil/biodiesel blend) and a bio-oil rich fraction. The results has shown that the compounds (mainly phenolic) extracted from bio-oil into the biodiesel-rich fraction reduces the surface tension of the resulted biodiesel/bio-oil blends that are known as potential liquid transport fuels. The bio-oil rich fraction is mixed with ground biochar to produce a bioslurry fuel. It is found that bioslurry fuels with 10% and 20% biochar loading prepared from the bio-oil rich fraction of biodiesel extraction at a biodiesel to bio-oil blend ratio 0.67 have similar fuel properties (e.g. density, surface tension, volumetric energy density and stability) in comparison to those prepared using the original whole bio-oil. The slurry fuels have exhibited non-Newtonian with pseudoplastic characteristics and good pumpability desirable for fuel handling. The viscoelastic behaviour of the slurry fuels also has shown dominantly fluid-like behaviour in the linear viscoelastic region therefore favourable for atomization in practical applications. This study proposes a new bio-oil utilisation strategy via coproduction of a biodiesel/bio-oil blend and a bioslurry fuel. The biodiesel/bio-oil blend utilises a proportion of bio-oil compounds (relatively high value small volume) as a liquid transportation fuel. The bioslurry fuel is prepared by mixing the rest low-quality bio-oil rich fractions (relatively low value and high volume) with ground biochar, suitable for stationary applications such as combustion and gasification.Overall, the present research has generated valuable data, knowledge and fundamental understanding on advanced fuels from mallee biomass using pyrolysis as a pre-treatment step. The flexibility of pyrolysis process enables conversion of bulky, low fuel quality mallee biomass to biofuels of high volumetric energy density favourable to reduce logistic cost associated with direct use of biomass. The significance structural, fuel and ash properties differences among various mallee biomass components were also revealed. The production of bioslurry fuels as a mixture of bio-oil and biochar is not only to further enhance the transportability/handling of mallee biomass but most importantly the slurry quality highly matched requirements in stationary applications such as combustion and gasification. The co-production of bioslurry with bio-oil/biodiesel extraction was firstly reported in this field. Such a new strategy, which uses high-quality extractable bio-oil compounds into bio-oil/biodiesel blend as a liquid transportation fuel and utilises the low-quality bio-oil rich fraction left after extraction for bioslurry preparation, offers significant benefits for optimised use of bio-oil.
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Verma, Saket. "Experimental investigation and exergy analysis of a dual fuel engine using alternative fuels." Thesis, IITD, 2019. http://eprint.iitd.ac.in:80//handle/2074/8099.
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Ion, Robert Aurelian. "Fuel depletion analyses at the Missouri University Research Reactor." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/5903.
Full textAbstract:
Thesis (Ph. D.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (March 2, 2007) Vita. Includes bibliographical references.
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McHenry, John Carl Izaak. "The Challenges of Biofuels in Ohio: From the Perspective of Small-Scale Producers." Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1197926303.
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Shelby, Michael H. (Michael Howard). "PLIF investigation of the fuel distribution in gasoline direct injection fuel sprays." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43930.
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Welling, Orian (Orian Z. ). "Thin fuel film reactor testing for characterization of diesel fuel deposit formation." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54481.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 29-30).
The need for specialized diesel fuel injectors is growing with increased efficiency and emissions regulation. These specialized fuel injectors have nozzle diameters of 150-200[mu]m which are susceptible to clogging from deposit formation. This thesis studies the deposit formation mechanisms with a thin fuel film reactor, and examines the potential for use of the reactor as a detergent screening tool. Through experimentation with the thin fuel film reactor it was found that temperature had negligible effect on the weight of a fully dried fuel film. This suggests that testing could be conducted at high or low temperatures to decrease the cycle time or increase test resolution respectively. It was also determined that dry deposits remain soluble in hot fuel immediately following drying, but become insoluble after long hot soak periods. A simple deposit formation model was constructed based on hypothesized formation factors. Although very simplified, the model matched the experimental results well. The correlation suggest that the hypothesized formation factors are critical to the formation process. The model should be expanded to explain deposit formation more generally, and further research should be conducted to better validate the model.
by Orian Welling.
S.B.
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Sheikhansari, Abdolkarim. "Evaluation of solid oxide fuel cells operating on hydrogen sulfide contaminated fuel." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/17699/.
Full textAbstract:
This research was conducted to investigate the effect of hydrogen sulfide on the performance of single solid oxide fuel cells. A test rig was designed and commissioned to test 5x5 cm2 cells (active area: 4x4 cm2). The test rig consists of a gas blender, a humidifier, a high temperature furnace, fuel and air manifolds and a control/data logging system. The characterisation techniques used in this project, include v-i measurement, EIS and SEM/EDX analysis. The first series of experiments were carried out to investigate the effect of time, hydrogen partial pressure and temperature on the performance of the cells operating on clean fuel. The results showed that the current of lowest resistance is independent of the operating temperature, however, depends on partial pressure of H2 and tends to increase as PH2 rises. The lowest resistance of the cell occurs at almost constant fuel utilization which was equal to 17 % in this research. In the second series of tests, the cells were exposed to a range of H2S concentrations i.e. 50, 100, 150 and 200 ppm. The composition of the fuel mixture was 0.1 nl/min (14.5 %) of H2, 0.567 nl/min (82.5 %) of N2 and 0.020 nl/min (3 %) of H2O (steam). All the contamination tests were carried out at 700 ˚C. The cells were exposed to H2S for 12 hours followed by a recovery period for 24 hours. The results revealed that the voltage drop at the end of the exposure period was similar for all degrees of poisoning. However, the performance at the end of the recovery, was different. The degree of recovery tended to decrease as the concentration of H2S increased. The SEM analysis of samples showed that H2S has caused the anode structure to change. This change occurred at the interface of anode functioning and support layers and was more severe at higher concentrations of H2S. In addition, two contamination models were developed based on the H2S degradation mechanism. The models considered the effects of time and H2S concentration. However, they could not predict the performance of the poisoned cells as the voltage drop at the end of exposure time was independent of the H2S concentration for the tested range.
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Eriksson, John, and Mårten Wallengren. "Model Based Control Algorithm for a Bi-Fuel Engine with fuel adjustment." Thesis, KTH, Maskinkonstruktion (Inst.), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141183.
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For lite mer an 100 ar sedan rullade den forsta serietillverkade bilen, i den helt valbara fargen svart, av monteringslinan. Sedan dess har ett febrilt utveckingsarbete gjorts for att forbattra alla delar av bilen. Forst endast i marknadsforingssyfte med storre motorer och mer komfort, men de senaste decennierna aven som svar pa utokade lagkrav runt om i varlden for att fa salja pa respektive marknader. En av de metoder som pa senare tiden har vuxit for att minska bilarnas utslapp ar att ga over ifran bensin och diesel till alternativa branslen. Da finns det bade fornyelsebara samt icke fornyelsebara, men med hogre verkningsgrad an konventionella branslen, att valja pa. For att stodja denna utveckling sa har Anstalt fur Verbrennungskraftmaschinen List (AVL) beslutat att fortsatta utveckla sin motorstyrvara, kallad Rap2L for att aven kunna styra motorer drivna av Compressed Natural Gas (Komprimerad naturgas) (CNG). Detta arbete syftar till att utveckla en modular gasfunktionalitet som bade ska kunna anvandas for att kora Rap2L, men aven enkelt kunna flyttas over till ett annat motorstyrsystem om onskan for det skulle uppkomma.A little more than a hundred years ago the first mass produced car rolled of the assembly line, in the optional color black, and since then a hectic race has been going on in order to improve all parts of the car. First only as a competitive edge with bigger engines and more comfort for the passengers, but in the last decades also as a response to increased legislation's around the world in order to be able to sell to their respective market. Apart from increasing the effectiveness of both engine and catalyst in order to meet the ever increasing environmental demands, there is also the possibility of exchanging the fuel used. One prominent alternative here is Compressed Natural Gas (CNG), that can be extracted both from natural gas or biogas, dependent on what available resources are at hand. In order to accommodate this change in fuel Anstalt fur Verbrennungskraftmaschinen List (AVL) has the desire to further develop its engine control software Rap2L, inorder to also be able to run CNG engines. The purpose for this thesis is to build a separate add-on to Rap2L where all the functionality for CNG is handled, it should also be able to, with minimal effort, be transported to another engine control system, if so desired.
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Bath, Andrew. "Performance Characterization of Complex Fuel Port Geometries for Hybrid Rocket Fuel Grains." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1381.
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This research investigated the 3D printing and burning of fuel grains with complex geometry and the development of software capable of modeling and predicting the regression of a cross-section of these complex fuel grains. The software developed did predict the geometry to a fair degree of accuracy, especially when enhanced corner rounding was turned on. The model does have some drawbacks, notably being relatively slow, and does not perfectly predict the regression. If corner rounding is turned off, however, the model does become much faster; although less accurate, this method does still predict a relatively accurate resulting burn geometry, and is fast enough to be used for performance-tuning or genetic algorithms. In addition to the modeling method, preliminary investigations into the burning behavior of fuel grains with a helical flow path were performed. The helix fuel grains have a regression rate of nearly 3 times that of any other fuel grain geometry, primarily due to the enhancement of the friction coefficient between the flow and flow path.
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Tshizanga, Ngoya. "A study of biodiesel production from waste vegetable oil using eggshell ash as a heterogeneous catalyst." Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2153.
Full textAbstract:
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology.While biodiesel has the potential to resolve the energy crisis, its production is hampered by both feedstock and catalyst availability. The aim of this current study is to investigate the production of biodiesel from waste vegetable oil (WVO) as feedstock under heterogeneous catalysis, mediated by calcined eggshell ash. WVO, characterised by 9% free fatty acid (FFA) and 0.17wt% water content, was employed as feedstock in the biodiesel production via transesterification reaction. The composition of WVO was determined using Gas chromatography (GC) analysis. The eggshell was washed with distilled water to remove impurities, dried in an oven at 105°C, and then crushed into fine particle of 75μm, and finally, calcined in a muffle furnace at 800°C. The chemical properties of the catalyst were assessed as follows: 1) using X-ray diffraction (XRD) to determine the major component phase of the element; 2) using X-ray fluorescent (XRF) to determine the elemental composition of the eggshell ash; 3) using Brunauer Emmet Teller (BET) to define the structure, the surface area, pore volume and pore diameter of the eggshell ash; and 4) using SEM to show the morphology structure of the element. The XRD analysis performed on eggshell ash showed 86% CaO as a major component in the catalyst; the remaining 14% was composed of MgO, SiO2, SO3, P2O5, Na2O, Al2O3, K2O and Fe2O3, as obtained from XRF. The BET result of the catalyst prepared was characterised by large pore diameter (91.2 Å) and high surface area (30.7m2/g), allowing reactants to diffuse easily into the interior of the catalyst used